Biology subjects

Ahern, D.

Publications and source records attributed to Ahern, D..

5 recordsLinked to original sources

bioRxiv2025

Innate antiviral readiness drives the expansion of protective T stem cell memory against influenza

The development of T-cell-based influenza vaccines relies on eliciting broad CD8+ T-cell immunity, wherein T stem cell-like memory (TSCM) cells serve as the ultimate long-lived reservoir for immune memory, thereby unlocking the potential for durable protection against viral drift and shift. However, the specific immunological cues that drive the robust expansion and functional preservation of this self-renewing, multipotent subset remain unknown. Here, utilizing multi-omic systems immunology in a pediatric cohort immunized with live attenuated influenza vaccine, we identified the determinants governing the expansion of influenza virus-reactive TSCM cells. We show that a pre-existing state of innate antiviral readiness, defined by a plasmacytoid dendritic cell-associated type I interferon signature, is the requisite condition for a robust TSCM expansion. Mechanistically, this baseline innate state enhances antigen priming and enforces a qualitative divergence in T-cell fate, driving responders toward a functionally poised, Th1-dominant phenotype while non-responders default to a dysfunctional, hyper-proliferative state. To determine the clinical relevance of this cellular subset, we analyzed an independent controlled human influenza challenge study. This validation revealed a critical functional division of labor in host defense: whereas pre-existing antibodies primarily mitigated symptom severity, the baseline frequency of influenza virus-reactive TSCM cells was the strongest predictor of rapid viral load clearance. These findings establish that the expansion of durable cellular memory is not stochastic but is predetermined by the innate cytokine environment, providing a predictive biomarker for patient stratification and a validated target for adjuvants designed to expand the TSCM reservoir deliberately.

immunology↗

bioRxiv2025

Divergent granulopoiesis at extramedullary sites safeguards host defense

Extramedullary organs such as the spleen can assume granulopoiesis as a supportive mechanism to cope with the demands during persistent inflammation. However, the quantitative output of extramedullary granulopoiesis is limited, thus raising the question if the spleen in fact provides neutrophils of a qualitative difference rather than merely contributing to neutrophil numbers. Here we report splenic stress granulopoiesis with distinct production and differentiation trajectories. Myeloid progenitors in the spleen engage in accelerated production of neutrophils with an immature phenotype. Yet, neutrophils generated during persistent stress granulopoiesis are fully competent to exert antimicrobial functions and are necessary to contain bacterial invasion. Activation of type I interferon signaling in the spleen is required for splenic neutrophil production and its loss impairs host defense. Thus, the spleen provides an immunological environment for stress-induced rapid production and priming of highly active neutrophils to meet the demands during infection.

immunology↗

bioRxiv2024

High-dimensional mass cytometry reveals stemness state heterogeneity in pancreatic ductal adenocarcinoma

Stem-like cancer cells harbour high self-renewal capacity, exhibit enhanced tumourigenicity and have been associated with therapy resistance, metastasis and tumour relapse. Therefore, understanding the molecular features of stem-like cells is critical for targeting them effectively and improving treatment outcomes for cancer patients. Several markers have been used to isolate and study the putative stem-like cells of pancreatic ductal adenocarcinoma (PDAC), but the patterns of marker co-expression and overlap between identified individual subpopulations are yet to be comprehensively studied. Here we developed a mass cytometry antibody panel for simultaneous analysis of 33 stemness-associated markers at single-cell resolution. High-dimensional mass cytometry analysis of PDAC cell lines revealed molecularly heterogeneous stemness states and highlighted the role of genotype in determining the cell line-specific stemness signature. Stemness marker expression lie along a continuum in PDAC cell lines and patient samples indicative of stepwise phenotypic transitions. We also identified a subset of PDAC cells co-expressing high levels of Musashi-2, DCLK1 and CXCR4, and harbouring basal-like and EMT transcriptional programmes associated with highly plastic phenotype. This multiplexed analysis uncovers nuance and complexities of the stemness state in the PDAC.

cancer biology↗

bioRxiv2020

Immune responses in pancreatic cancer may be restricted byprevalence of activated regulatory T-cells, dysfunctionalCD8+ T-cells, and senescent T-cells

Pancreatic cancer has the worst prognosis of any human malignancy and leukocyte infiltration is a major prognostic marker of the disease. As current immunotherapies confer negligible survival benefits, there is a need to better characterise leukocytes in pancreatic cancer to identify better therapeutic strategies. In this study, we analysed 32 human pancreatic cancer patients from two independent cohorts. A multi-parameter mass-cytometry analysis was performed on 32,000 T-cells from eight patients. Single-cell RNA sequencing dataset analysis was performed on a cohort of 24 patients. Multiplex immunohistochemistry imaging and spatial analysis were performed to map immune infiltration into the tumour microenvironment. Regulatory T-cell populations demonstrated highly immunosuppressive states with high TIGIT, ICOS and CD39 expression. CD8+ T-cells were found to be either in senescence or an exhausted state. The exhausted CD8 T-cells had low PD-1 expression but high TIGIT and CD39 expression. These findings were corroborated in an independent pancreatic cancer single-cell RNA dataset from additional 24 patients. These data suggest that T-cells are major players in the suppressive microenvironment of pancreatic cancer. Our work identifies novel therapeutic targets that should form the basis for rational design of a new generation of clinical trials in pancreatic ductal adenocarcinoma.

immunology↗

bioRxiv2019

Histone H3K27me3 demethylases regulate human Th17 cell development and effector functions by impacting on metabolism

T helper (Th) cells are CD4+ effector T cells that play an instrumental role in immunity by shaping the inflammatory cytokine environment in a variety of physiological and pathological situations. Using a combined chemico-genetic approach we identify histone H3K27 demethylases KDM6A and KDM6B as central regulators of human Th subsets. The prototypic KDM6 inhibitor GSK-J4 increases genome-wide levels of the repressive H3K27me3 chromatin mark and leads to suppression of the key transcription factor ROR{gamma}t during Th17 differentiation, whereas in mature Th17 cells an altered transcriptional program leads to a profound metabolic reprogramming with concomitant suppression of IL-17 cytokine levels and reduced proliferation. Single cell analysis reveals a specific shift from highly inflammatory cell subsets towards a resting state upon demethylase inhibition. The root cause of the observed anti-inflammatory phenotype in stimulated Th17 cells is reduced expression of key metabolic transcription factors, such as PPRC1 and c-myc. Overall, this leads to reduced mitochondrial biogenesis resulting in a metabolic switch with concomitant anti-inflammatory effects. These data are consistent with an opposing effect of GSK-J4 on Th17 T-cell differentiation pathways directly related to proliferation and effector cytokine profiles.

immunology↗